Catch the stream of the selected device

Question

I need to get the audio stream played on the user’s phone/speakers and I’m finding a problem when it comes to getting the stream of the selected device. In short it is as follows: The phone ends up having the same microphone id 'Default' and the return of 'Navigator.mediaDevices.getUserMedia' even sending the device ends up becoming the microphone return.

this.start = function () {
    return navigator.mediaDevices.getUserMedia({
        audio: true
    })
    .then(function (objStream) {
        navigator.mediaDevices.enumerateDevices().then(function (objDevices) {
            var objAudio = objDevices.find(function (objDevice) {
                return objDevice.kind == "audiooutput";
            });

            objStream.getTracks().forEach(function (objMidiaAudio) {
                objMidiaAudio.stop();
            });

            if (objAudio) {
                return navigator.mediaDevices.getUserMedia({
                    audio: objAudio
                });
            }

            return navigator.mediaDevices.getUserMedia({
                audio: true
            });
        })
    .then(function (objStream) {
        new Promise(function () {
            var audio = objStream.getAudioTracks()[0];

This would be the code snippet where I’m having trouble, the objAudio variable, had the phone, but when I return to the 'then' the objStream has the microphone. Any suggestions on how to get around this problem?